Mixtures of optical brighteners

ABSTRACT

Mixtures of optical brighteners consisting of 5 to 95% by weight of a compound of the formula ##STR1## in which A denotes a o- or p-cyanophenyl group, and 95 to 5% by weight of one or more further optical brighteners.

Mixtures of optical brighteners from the series of the 1,4-bis-(cyanostyryl)-benzenes and of the 4-alkoxynaphthalimides have already been disclosed in Japanese Patent Application Sho No. 50(1975)-25 877.

The present invention relates to mixtures of optical brighteners which have improved properties and consist of 0.05-0.95 parts by weight of a compound of the formula 1 ##STR2## in which A denotes a o- or p-cyanophenyl group, and 0.95 to 0.05 parts by weight of one or more compounds of the formulae 2, 3, 4, 5 or 6 ##STR3## in which n denotes 0 or 1, X denotes an oxygen or sulfur atom, R₁ and R₂ denote identical or different radicals from the group comprising hydrogen, fluorine or chlorine atoms, phenyl, trifluoromethyl, C₁ -C₉ alkyl, alkoxy, dialkylamino, acylamino, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester, it being possible for two adjacent radicals R₁ and R₂ together also to represent a benzo ring, a lower alkylene group or a 1,3-dioxapropylene group, B denotes cyano, a group of the formula --COOR₁₁ or CONR₁₁ R₁₁ in which R₁₁ denotes hydrogen, C₁ -C₁₈ alkyl, cycloalkyl, aryl, alkylaryl, halogenoaryl, aralkyl, alkoxyalkyl, halogenoalkyl, hydroxyalkyl, alkylaminoalkyl, carboxyalkyl or carboalkoxyalkyl, or two alkyl or alkylene radicals with the meaning of R₁₁ can also form, together with the nitrogen atom, a morpholine, piperidine or piperazine ring, or B denotes a group of the formula ##STR4## in which R₁₂ and R₁₃ denote identical or different radicals from the group comprising hydrogen, fluorine or chlorine atoms, phenyl, alkyl, alkoxy, acylamino, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester, it being possible for two adjacent radicals R₁₂ and R₁₃ together also to represent an alkylene group, a fused benzo ring or a 1,3-dioxapropylene group, or B denotes a group of the formulae ##STR5## in which R₁₄ denotes a straight-chain or branched alkyl group having 1-18 C atoms and preferably 1-6 C atoms, which can be substituted by hydroxyl groups, halogen atoms or alkoxy, dialkylamino, alkylmercapto, chloroaryloxy, aryloxy, arylmercapto or aryl radicals, it being possible in the case of the dialkylamino alkyl groups for the two alkyl groups together also to form a morpholine, piperidine or piperazine ring, or R₁₄ denotes a group of the formula --(CH₂ CH₂ O)_(n) --R, in which n is 1, 2 or 3 and R is H, alkyl, dialkylaminoalkoxyalkyl or alkylthioalkoxyalkyl, it being possible for the dialkyl groups in dialkylaminoalkoxyalkyl together to form a piperidine, pyrrolidine, hexamethyleneimine, morpholine or piperazine ring, or R₁₄ denotes a radical of the formula ##STR6## R₂₂ denotes a hydrogen atom, a triphenylmethyl group or a lower alkyl radical, which is optionally substituted by a lower carbalkoxy, carboxamido, mono- or di-alkylcarboxamido, carboxyl or benzoyl group, and R₂₃ denotes a cyano group or a group of the formulae ##STR7## in which R', R" and R"' denote a hydrogen atom, a lower alkyl radical or a phenyl radical, and it being possible for the lower alkyl radicals to be substituted by hydroxyl, lower alkoxy, lower dialkylamino or lower trialkylammonium groups and for the phenyl group to be substituted by halogen atoms or lower alkyl or lower alkoxy groups, and in which R" and R"' together can also form a saturated divalent radical, Y denotes O, S or N--R, in which R is H or (C₁ to C₄)-alkyl, or B denotes a group of the formula ##STR8## in which R₁₅ denotes a phenyl ring, which can be substituted by one or two chlorine atoms, one or two alkyl or alkoxyalkyl groups or one phenyl, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester group, R₃ and R₄ can be identical or different and denote hydrogen, alkyl, cycloalkyl, alkoxy, hydroxyalkoxyethyl, halogenoalkyl, aralkyl, aryl or N,N-di-alkylamine, or R₃ and R₄ together form a five-membered heterocyclic radical having 1 to 3 hetero-atoms, preferably N atoms, R₅ denotes straight-chain or branched alkyl, alkoxyalkyl, dialkylaminoalkyl or a radical of the formula ##STR9## in which R₁₆ is hydrogen, C₂ -C₈ -alkanoyl, benzoyl or a radical of the formula R₁₈ NHCO-- or R₁₉ OCO-- and R₁₇ is hydrogen, alkyl or phenyl, R₁₈ is alkyl, phenyl, halogenophenyl or tolyl and R₁₉ is C₁ -C₈ -alkyl, alkoxyalkyl, cyclohexyl, benzyl, phenylethyl or phenyl which is optionally substituted by non-chromophoric substituents, or R₅ denotes a radical of the formula ##STR10## in which R₂₀ is C₁ -C₁₀ -alkyl, C₂ -C₆ -alkenyl, C₂ -C₆ -alkinyl, C₁ -C₈ -alkoxy, C₁ -C₈ -alkylamino or dialkylamino, phenoxymethyl, phenyl, tolyl, benzyl or phenylethyl and R₂₁ is C₃ -C₁₀ -alkyl, which can be substituted by phenyl, hydroxyphenyl, methoxy or dimethoxy, R₆ denotes an aryl radical, which is optionally substituted by non-chromophoric substituents, or denotes a 1,2,4-triazol-1-yl-phenyl, 1,2,3-triazol-4-yl-phenyl, 1,2,3-triazol-3-yl-phenyl or 1,2,3-triazol-2-yl-phenyl radical, which can optionally be substituted by 1 or 2 C₁ -C₃ -alkyl or oxalkyl groups or by oxaryl, oxalkenyl or oxalkanoyl, or R₆ denotes a heterocyclic ring having 1-3 hetero-atoms, preferably N or O, which can be substituted by alkyl, alkoxy, halogen, aryl or halogenoaryl, or R₆ denotes a 1-oxa-2,4-diazol-5-yl radical, which can be substituted by benzyl, alkoxyphenyl, styryl, halogen, alkoxy or a further heterocyclic group, or R₆ denotes a benzimidazol-1-yl, benzimidazol-2-yl, benzthiazol-1-yl or benzthiazol-2-yl radical, which can be substituted by non-chromophoric substituents, R₇ denotes hydrogen, alkyl, alkoxy, aryl or a five-membered heterocyclic radical which has 1-3 N or O hetero-atoms and is bonded via a nitrogen atom and can be substituted by alkyl, aryl, hydroxyl, oxalkyl, oxalkenyl, oxaryl, oxarylalkyl, oxalkoxycarbonyl, oxcarbamoyl, oxepoxyalkyl, styryl or halogenostyryl, a fused phenyl, naphthyl or phenanthryl ring or a fused group of the formulae ##STR11## and the aromatic rings in the fused groups can also be substituted by alkyl or alkoxy and X is oxygen, NH or N-alkyl, R₈ represents a polycyclic, aromatic radical having at least three fused rings, which optionally carry non-chromophoric substituents, R₉ represents an amino group, which is substituted by one or two alkyl, hydroxyalkyl, acyl or phenyl groups, it being possible for the phenyl group to contain one or more non-chromophoric radicals and for two alkyl groups, together with the nitrogen atom of the amino group, to form a pyrrolidine or piperidine ring or, with the inclusion of a further nitrogen or oxygen atom, a piperazine or morpholine ring, or R₉ represents an alkoxy, hydroxyalkoxy, acyloxy, alkylthio or carbalkylmercapto group, R₁₀ independently of R₈ has the same meaning as R₉ and in addition can denote a chlorine atom and V denotes a group of the formulae ##STR12##

Preferred compounds of the formula 1 are those in which A represents a p-cyanophenyl group.

Unless defined otherwise, alkyl and alkoxy groups and also other groups derived therefrom contain 1 to 4 C atoms. The term "non-chromophoric substituents" is to be understood as meaning alkyl, alkoxy, aryl, aralkyl, trifluoromethyl, cycloalkyl, halogen, alkylsulfonyl, carboxyl, sulfonic acid, cyano, carboxamide, sulfonamide, carboxylic acid alkyl ester and sulfonic acid alkyl ester.

Of the compounds under the formulae 2 to 6, the compounds of the following formulae are preferred in the mixtures according to the invention: ##STR13## in which R_(1') and R_(2') in the 5-position and 7-position denote hydrogen or chlorine, alkyl or phenyl, or together denote a fused phenyl ring, X denotes oxygen or sulfur, n denotes 1 and B denotes a group of the formulae ##STR14## in which R_(14') denotes alkyl, chloroalkyl, alkoxyalkyl, hydroxyalkyl or a group of the formula --(CH₂ CH₂ O)_(n) --R, in which n is 2 or 3 and R is hydrogen or alkyl, R₁₅ ' denotes phenyl, which can be substituted by one or two chlorine atoms, one or two alkyl or alkoxyalkyl groups or one phenyl, cyano, carboxylic acid, carboalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester group, R₂₃ denotes cyano or carboalkoxy and R₂₂ denotes alkyl. ##STR15## in which R_(3') denotes hydrogen or alkoxy, R_(4') denotes alkoxy and R_(5') denotes alkyl, alkoxyalkyl or dialkylaminoalkyl. ##STR16## in which R_(6') denotes phenyl or the group of the formula ##STR17## and R_(7') denotes the groups of the formulae ##STR18## in which R_(1') and R_(2') denote hydrogen or alkyl and V' denotes a group of the formulae ##STR19## and X denotes O or S.

Further preferred mixtures, according to the invention, of optical brighteners are those consisting of a compound of the formula 1a ##STR20## and one or more compounds of the formulae 2b-6b ##STR21## in which R₁ in the 5-position denotes a hydrogen or chlorine atom or a methyl or phenyl group and R₂ denotes a hydrogen atom, or R₁ and R₂ both denote a methyl group in the 5,6- or 5,7-position, n denotes 0 or 1 and B denotes a cyano or carbo-(C₁ -C₄)-alkoxy group or a group of the formulae ##STR22## in which R₁₄ denotes (C₁ -C₆)-alkyl, (C₁ -C₆)-chloroalkyl, (C₁ -C₄)-alkoxy-(C₁ -C₄)-alkyl, hydroxy-(C₁ -C₄)-alkyl or a group of the formula --(CH₂ CH₂ O)_(n) --R, n denotes 2 or 3 and R denotes hydrogen or (C₁ -C₄)-alkyl, R₁₅ denotes phenyl, halogenophenyl, (C₁ -C₄)-alkylphenyl or (C₁ -C₄)-alkoxyphenyl, R₂₂ denotes (C₁ -C₄)-alkyl and R₂₃ denotes cyano or carbo-(C₁ -C₄)-alkoxy, ##STR23## in which R₃ denotes hydrogen or (C₁ -C₄)-alkoxy, R₄ denotes (C₁ -C₄)-alkoxy and R₅ denotes (C₁ -C₆)-alkyl or (C₁ -C₄)-alkoxy-(C₁ -C₄)-alkyl, ##STR24## in which R₆ denotes phenyl or the group of the formulae ##STR25## and R₇ denotes a group of the formula ##STR26## in which R₁ represents hydrogen or (C₁ -C₄)-alkyl and R₂ represents phenyl or (C₁ -C₄)-alkoxy, or R₁ and R₂ together represent a benzo or (1,2-d)-naphtho ring, ##STR27## in which R₈ denotes the pyrenyl group and R₉ and R₁₀ denote (C₁ -C₄)-alkoxy, and ##STR28## in which R₁ and R₂ have the same meaning as in formula 2b and V denotes a group of the formulae ##STR29##

Further preferred mixtures of optical brighteners are those consisting of a compound of the formula 1a and one or more compounds of the following formulae ##STR30## in which R₁ and R₂ in the 5,6-position are methyl and B is carbomethoxy, or R₁ is hydrogen, R₂ is hydrogen or methyl in the 5-position and B is carbomethoxy, cyano or a group of the formulae ##STR31## in which R₁₄ and R₂₂ are (C₁ -C₃)-alkyl and R₁₅ is phenyl, 4-methylphenyl or 4-methoxyphenyl, or R₁ is hydrogen, methyl or t-butyl in the 5-position, R₂ is hydrogen or methyl in the 7-position and B is phenyl, ##STR32## in which R₃ is hydrogen or methoxy, ##STR33## in which R₂ is hydrogen or methyl.

Of the compounds under the formula 2, those which are very particularly preferred are the compounds of the formula ##STR34## in which R_(1") and R_(2") denote hydrogen or alkyl and B" denotes a group of the formulae ##STR35## and R_(14") denotes alkyl or methoxyethyl. The following compounds under the formula 2: ##STR36## are of particular importance.

The mixing ratio for the individual components is between 0.05 and 0.95, preferably 0.20-0.80 parts by weight for the compounds of the formula 1 and correspondingly 0.95 to 0.05, preferably 0.80-0.20 parts by weight for the other compounds of the formulae 2 to 6. These compounds of the formulae 2 to 6 can be employed on their own, but can also be employed in any desired mixture with one another; the mixing ratio of these compounds with one another is entirely non-critical and can be varied as desired. The same applies in the case of the two brighteners which fall under formula 1 and which can be employed either on their own or as a mixture in any conceivable mixing ratio.

In an individual case, the optimum mixing ratio of all of the compounds of the formulae 1 to 6 depends on the structure of the particular compounds and can be determined without difficulty by simple preliminary experiments.

As is customary in the case of optical brighteners, the individual components are brought into the commercial form by dispersing in a liquid medium, for example water. The individual components can each be dispersed on their own and the dispersions can then be added together. However, it is also possible to mix the individual components with one another as the solids and then to disperse them together. This dispersion process is effected in a conventional manner in ball mills, colloid mills, bead mills or dispersion kneaders. The mixtures according to the invention are particularly suitable for brightening textile material made of linear polyesters, polyamides and acetylcellulose. However, these mixtures can also be used with a good result on mixed fabrics which consist of linear polyesters and other synthetic or natural fiber materials, specifically fibers containing hydroxyl groups and in particular cotton. These mixtures are applied under the conditions customary for the use of optical brighteners, thus, for example, by the exhaustion process at 90° C. to 130° C. with or without the addition of accelerators (carriers) or by the thermosol process. The brighteners which are insoluble in water and the mixtures according to the invention can also be used as a solution in organic solvents, for example perchloroethylene or fluorinated hydrocarbons. The textile material can be treated by the exhaustion process with the solvent liquor which contains the optical brighteners in solution, or the textile material is impregnated, padded or sprayed with the solvent liquor containing the brightener and then dried at temperatures of 120°-220° C., during which operation the optical brighteners are fixed without residue in the fiber. Outstandingly brightened goods are obtained which have excellent stability to light and also stability to oxidizing agents and reducing agents. Compared with the mixtures of Japanese Patent Sho No. 50(1975)-25 877, these mixtures according to the invention have higher whiteness and already give outstanding whiteness at low temperatures, for example 150° C.

The following tabulated examples illustrate the invention. The method of application employed is described here by way of example:

Cut pieces of a fabric made of polyester staple fibers are washed and dried and impregnated on a padder with aqueous dispersions which contain either the pure optical brightener of the formulae 1-6 in an amount of 0.08% by weight or a mixture of 0.064% by weight, 0.04% by weight and 0.016% by weight of the brightener of the formula 1 with 0.016, 0.04 and 0.064% by weight, respectively of the brighteners of the formula 2-6.

The material is now squeezed off between rollers using a padder, so that the resulting moisture absorption is about 80%. This corresponds to a pick-up of optical brighteners on the goods of 0.064%. The material padded in this way was then subjected to a thermosol treatment on a tenter frame for 30 seconds at 170° C. (Table I) or 210° (Table II). The Ganz whiteness indicated in each case was obtained, and these degrees of whiteness are higher than the whiteness of the mixtures of the brightener types 2-6 with 1,4-bis-(2'-cyanostyryl)-benzene. The whiteness was measured using a Type DMC-25 spectrophotometer (Messrs. Carl Zeiss, Oberkochen).

    TABLE I         Amount of Amount of    brightener brightener Ganz Brightener 1      Brightener 2-6 1 used 2-6 used whiteness       ##STR37##       -- 0.08  206 --       ##STR38##       -- 0.08 206 " " 0.064 0.016 219 " " 0.04 0.04 221 " " 0.016 0.064 226       ##STR39##       -- 0.8 -- 236 " " 0.064 0.016 238 " " 0.04 0.04 236 " " 0.016 0.064 235      --       ##STR40##       -- 0.08 213       ##STR41##       ##STR42##       0.064 0.016 219 " " 0.04 0.04 218 " " 0.016 0.064 229       ##STR43##       ##STR44##       0.064 0.016 242       ##STR45##       ##STR46##       0.04 0.04 239 " " 0.016 0.64 234 --       ##STR47##       -- 0.08 215       ##STR48##       ##STR49##       0.064 0.016 219 " " 0.04 0.04 227 "  0.016 0.064 225       ##STR50##       " 0.064 0.016 240 " " 0.04 0.04 237 " " 0.016 0.064 229 --       ##STR51##       -- 0.08 207       ##STR52##       " 0.064 0.016 215 " " 0.04 0.04 219       ##STR53##       ##STR54##       0.016 0.064 222       ##STR55##       " 0.064 0.016 243 " " 0.04 0.04 237 " " 0.016 0.064 229 --       ##STR56##       -- 0.08 189       ##STR57##       " 0.064 0.016 215 " " 0.04 0.04 213 " " 0.016 0.064 214       ##STR58##       " 0.064 0.016 236 " " 0.04 0.04 234 " " 0.016 0.064 223       ##STR59##       ##STR60##       0.08 -- 213 " " 0.064 0.016 207 " " 0.04 0.04 219 " " 0.016 0.064 218      --       ##STR61##       -- 0.08 203       ##STR62##        0.064 0.016 203 " " 0.04 0.04 205 " " 0.016 0.064 200       ##STR63##       " 0.064 0.016 227 "  " 0.04 0.04 218 " " 0.016 0.064 212 --       ##STR64##       -- 0.08 244       ##STR65##       " 0.064 0.016 221 " " 0.04 0.04 232       ##STR66##       ##STR67##       0.016 0.064 245       ##STR68##        " 0.064 0.016 238 " " 0.04 0.04 242 " " 0.016 0.064 245

    TABLE II         Amount of Amount of    brightener brightener Ganz Brightener 1      Brightener 2-6 1 used 2-6 used whiteness       ##STR69##       -- 0.08  235 --       ##STR70##       -- 0.08 212 " " 0.064 0.016 230 " " 0.04 0.04 221 " " 0.016 0.064 223       ##STR71##       -- 0.8 -- 240 " " 0.064 0.016 241 " " 0.04 0.04 239 " " 0.016 0.064 233      --       ##STR72##       -- 0.08 221       ##STR73##       ##STR74##       0.064 0.016 233 " " 0.04 0.04 236 " " 0.016 0.064 225       ##STR75##       ##STR76##       0.064 0.016 240       ##STR77##       ##STR78##       0.04 0.04 240 " " 0.016 0.64 236 --       ##STR79##       -- 0.08 231       ##STR80##       ##STR81##       0.064 0.016 234 " " 0.04 0.04 235 " " 0.016 0.064 227       ##STR82##       " 0.064 0.016 243 " " 0.04 0.04 246 " " 0.016 0.064 244 --       ##STR83##       -- 0.08 207       ##STR84##       " 0.064 0.016 227 " " 0.04 0.04 231       ##STR85##       ##STR86##       0.016 0.064 224       ##STR87##       " 0.064 0.016 243 " " 0.04 0.04 240 " " 0.016 0.064 227 --       ##STR88##       -- 0.08 197       ##STR89##       " 0.064 0.016 237 " " 0.04 0.04 223 " " 0.016 0.064 215       ##STR90##       " 0.064 0.016 241 " " 0.04 0.04 239 " " 0.016 0.064 229       ##STR91##       ##STR92##       0.08 -- 232 " " 0.064 0.016 223 " " 0.04 0.04 230 " " 0.016 0.064 233      --       ##STR93##       -- 0.08 206       ##STR94##        0.064 0.016 233 " " 0.04 0.04 228 " " 0.016 0.064 227       ##STR95##       " 0.064 0.016 241 " " 0.04 0.04 229 " " 0.016 0.064 214 --       ##STR96##       -- 0.08 204       ##STR97##       " 0.064 0.016 228 " " 0.04 0.04 224       ##STR98##       ##STR99##       0.016 0.064 214       ##STR100##       " 0.064 0.016 234 " " 0.04 0.04 216 " " 0.016 0.064 204 

We claim:
 1. Mixtures of optical brighteners consisting of 0.05-0.95 parts by weight of a compounds of the formula 1 ##STR101## in which A denotes a o- or p-cyanophenyl group, and 0.95 to 0.05 parts by weight of one or more compounds of the formulae 2, 3, 4, 5 or 6 ##STR102## in which n denotes 0 or 1, X denotes an oxygen or sulfur atom, R₁ and R₂ denote identical or different radicals from the group comprising hydrogen, fluorine or chlorine atoms, phenyl, trifluoromethyl, C₁ -C₉ alkyl, alkoxy, dialkylamino, acylamino, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester, it being possible for two adjacent radicals R₁ and R₂ together also to represent a benzo ring, a lower alkylene group or a 1,3-dioxapropylene group, B denotes cyano, a group of the formula --COOR₁₁ or CONR₁₁ R₁₁ in which R₁₁ denotes hydrogen, C₁ -C₁₈ alkyl, cycloalkyl, aryl, alkylaryl, halogenoaryl, aralkyl, alkoxyalkyl, halogenoalkyl, hydroxyalkyl, alkylamino-alkyl, carboxyalkyl or carboalkoxyalkyl, or two alkyl or alkylene radicals with the meaning of R₁₁ can also form, together with the nitrogen atom, a morpholine, piperidine or piperazine ring, or B denotes a group of the formula ##STR103## in which R₁₂ and R₁₃ denote identical or different radicals from the group comprising hydrogen, fluorine or chlorine atoms, phenyl, alkyl, alkoxy, acylamino, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester, it being possible for two adjacent radicals R₁₂ and R₁₃ together also to represent an alkylene group, a fused benzo ring or a 1,3-dioxapropylene group, or B denotes a group of the formulae ##STR104## in which R₁₄ denotes a straight-chain or branched alkyl group having 1-18 C atoms and preferably 1-6 C atoms, which can be substituted by hydroxyl groups, halogen atoms or alkoxy, dialkylamino, alkylmercapto, chloroaryloxy, aryloxy, arylmercapto or aryl radicals, it being possible in the case of the dialkylamino alkyl groups for the two alkyl groups together also to form a morpholine, piperidine or piperazine ring, or R₁₄ denotes a group of the formula --(CH₂ CH₂ O)_(n) --R, in which n is 1, 2 or 3 and R is H, alkyl, dialkylaminoalkoxyalkyl or alkylthioalkoxyalkyl, it being possible for the dialkyl groups in dialkylaminoalkoxyalkyl together to form a piperidine, pyrrolidine, hexamethyleneimine, morpholine or piperazine ring, or R₁₄ denotes a radical of the formula ##STR105## R₂₂ denotes a hydrogen atom, a triphenylmethyl group or a lower alkyl radical, which is optionally substituted by a lower carbalkoxy, carboxamido, mono- or di-alkylcarboxamido, carboxyl or benzoyl group, and R₂₃ denotes a cyano group or a group of the formulae ##STR106## in which R', R" and R"' denote a hydrogen atom, a lower alkyl radical or a phenyl radical, and it being possible for the lower alkyl radicals to be substituted by hydroxyl, lower alkoxy, lower dialkylamino or lower trialkylammonium groups and for the phenyl group to be substituted by halogen atoms or lower alkyl or lower alkoxy groups, and in which R" and R"' together can also form a saturated divalent radical, Y denotes O, S or N-R, in which R is H or (C₁ to C₄)-alkyl, or B denotes a group of the formula ##STR107## in which R₁₅ denotes a phenyl ring, which can be substituted by one or two chlorine atoms, one or two alkyl or alkoxyalkyl groups or one phenyl, cyano, carboxyl, carbalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester group, R₃ and R₄ can be identical or different and denote hydrogen, alkyl, cycloalkyl, alkoxy, hydroxyalkoxyethyl, halogenoalkyl, aralkyl, aryl or N,N-di-alkylamine, or R₃ and R₄ together form a five-membered heterocyclic radical having 1 to 3 hetero-atoms, preferably N atoms, R₅ denotes straight-chain or branched alkyl, alkoxyalkyl, dialkylaminoalkyl or a radical of the formula ##STR108## in which R₁₆ is hydrogen, C₂ -C₈ -alkanoyl, benzoyl or a radical of the formula R₁₈ NHCO-- or R₁₉ OCO-- and R₁₇ is hydrogen, alkyl or phenyl, R₁₈ is alkyl, phenyl, halogenophenyl or tolyl and R₁₉ is C₁ -C₈ -alkyl, alkoxyalkyl, cyclohexyl, benzyl, phenylethyl or phenyl which is optionally substituted by non-chromophoric substituents, or R₅ denotes a radical of the formula ##STR109## in which R₂₀ is C₁ -C₁₀ -alkyl, C₂ -C₆ -alkenyl, C₂ -C₆ -alkinyl, C₁ -C₈ -alkoxy, C₁ -C₈ -alkylamino or dialkylamino, phenoxymethyl, phenyl, tolyl, benzyl or phenylethyl and R₂₁ is C₃ -C₁₀ -alkyl, which can be substituted by phenyl, hydroxyphenyl, methoxy or dimethoxy, R₆ denotes an aryl radical, which is optionally substituted by non-chromophoric substituents, or denotes a 1,2,4-triazol-1-yl-phenyl, 1,2,3-triazol-4-yl-phenyl, 1,2,3-triazol-3-yl-phenyl or 1,2,3-triazol-2-yl-phenyl radical, which can optionally be substituted by 1 or 2 C₁ -C₃ -alkyl or oxalkyl groups or by oxaryl, oxalkenyl or oxalkanoyl, or R₆ denotes a heterocyclic ring having 1-3 hetero-atoms, preferably N or 0, which can be substituted by alkyl, alkoxy, halogen, aryl or halogenoaryl, or R₆ denotes a 1-oxa-2,4-diazol-5-yl radical, which can be substituted by benzyl, alkoxyphenyl, styryl, halogen, alkoxy or a further heterocyclic group, or R₆ denotes a benzimidazol-1-yl, benzimidazol-2-yl, benzthiazol-1-yl or benzthiazol-2-yl radical, which can be substituted by non-chromophoric substituents, R₇ denotes hydrogen, alkyl, alkoxy, aryl or a five-membered heterocyclic radical which has 1-3 N or 0 hetero-atoms and is bonded via a nitrogen atom and can be substituted by alkyl, aryl, hydroxyl, oxalkyl, oxalkenyl, oxaryl, oxarylalkyl, oxalkoxycarbonyl, oxcarbamoyl, oxepoxyalkyl, styryl or halogenostyryl, a fused phenyl, naphthyl or phenanthryl ring or a fused group of the formulae ##STR110## and the aromatic rings in the fused groups can also be substituted by alkyl or alkoxy and X is oxygen, NH or N-alkyl, R₈ represents a polycyclic, aromatic radical having at least three fused rings, which optionally carry non-chromophoric substituents, R₉ represents an amino group, which is substituted by one or two alkyl, hydroxyalkyl, acyl or phenyl groups, it being possible for the phenyl group to contain one or more non-chromophoric radicals and for two alkyl groups, together with the nitrogen atom of the amino group, to form a pyrrolidine or piperidine ring or, with the inclusion of a further nitrogen or oxygen atom, a piperazine or morpholine ring, or R₉ represents an alkoxy, hydroxyalkoxy, acyloxy, alkylthio or carbalkylmercapto group, R₁₀ independently of R₈ has the same meaning as R₉ and in addition can denote a chlorine atom and V denotes a group of the formulae ##STR111##
 2. Mixtures of optical brighteners as claimed in claim 1, consisting of a compound of the formula ##STR112## and one or more compounds of the formulae 2a-6a ##STR113## in which R_(1') and R_(2') in the 5-position and 7-position denote hydrogen or chlorine, alkyl or phenyl, or together denote a fused phenyl ring, X denotes oxygen or sulfur, n denotes 1 and B denotes a group of the formulae ##STR114## in which R_(14') denotes alkyl, chloroalkyl, alkoxyalkyl, hydroxyalkyl or a group of the formula --(CH₂ CH₂ O)_(n) --R, in which n is 2 or 3 and R is hydrogen or alkyl, R_(15') denotes phenyl, which can be substituted by one or two chlorine atoms, one or two alkyl or alkoxyalkyl groups or one phenyl, cyano, carboxylic acid, carboalkoxy, carboxamide, sulfonic acid, sulfonamide or sulfonic acid alkyl ester group, R₂₃ denotes cyano or carboalkoxy and R₂₂ denotes alkyl, ##STR115## in which R_(3') denotes hydrogen or alkoxy, R_(4') denotes alkoxy and R_(5') denotes alkyl, alkoxyalkyl or dialkylaminoalkyl, ##STR116## in which R_(6') denotes phenyl or the group of the formula ##STR117## and R_(7') denotes the groups of the formulae ##STR118## in which R_(1') and R_(2') denote hydrogen or alkyl and V' denotes a group of the formulae ##STR119## and X denotes 0 or S.
 3. Mixtures of optical brighteners as claimed in claim 1, consisting of a compound of the formula 1a ##STR120## and one or more compounds of the formulae 2b-6b ##STR121## in which R₁ in the 5-position denotes a hydrogen or chlorine atom or a methyl or phenyl group and R₂ denotes a hydrogen atom, or R₁ and R₂ both denote a methyl group in the 5,6- or 5,7-position, n denotes 0 or 1 and B denotes a cyano or carbo-(C₁ -C₄)-alkoxy group or a group of the formulae ##STR122## in which R₁₄ denotes (C₁ -C₆)-alkyl, (C₁ -C₆)-chloroalkyl, (C₁ -C₄)-alkoxy-(C₁ -C₄)-alkyl, hydroxy-(C₁ -C₄)-alkyl or a group of the formula --(CH₂ CH₂ O)_(n) --R, n denotes 2 or 3 and R denotes hydrogen or (C₁ -C₄)-alkyl, R₁₅ denotes phenyl, halogenophenyl, (C₁ -C₄)-alkylphenyl or (C₁ -C₄)-alkoxyphenyl, R₂₂ denotes (C₁ -C₄)-alkyl and R₂₃ denotes cyano or carbo-(C₁ -C₄)-alkoxy, ##STR123## in which R₃ denotes hydrogen or (C₁ -C₄)-alkoxy, R₄ denotes (C₁ -C₄)-alkoxy and R₅ denotes (C₁ -C₆)-alkyl or (C₁ -C₄)-alkoxy-(C₁ -C₄)-alkyl, ##STR124## in which R₆ denotes phenyl or the group of the formulae ##STR125## and R₇ denotes a group of the formula ##STR126## in which R₁ represents hydrogen or (C₁ -C₄)-alkyl and R₂ represents phenyl or (C₁ -C₄)-alkoxy, or R₁ and R₂ together represent a benzo or (1,2-d)-naphtho ring, ##STR127## in which R₈ denotes the pyrenyl group and R₉ and R₁₀ denote (C₁ -C₄)-alkoxy, and ##STR128## in which R₁ and R₂ have the same meaning as in formula 2b and V denotes a group of the formulae ##STR129##
 4. Mixtures of optical brighteners as claimed in claim 1, consisting of a compound of the formula 1a and one or more compounds of the following formulae ##STR130## in which R₁ and R₂ in the 5,6-position are methyl and B is carbomethoxy, or R₁ is hydrogen, R₂ is hydrogen or methyl in the 5-position and B is carbomethoxy, cyano or a group of the formulae ##STR131## in which R₁₄ and R₂₂ are (C₁ -C₃)-alkyl and R₁₅ is phenyl, 4-methylphenyl or 4-methoxyphenyl, or R₁ is hydrogen, methyl or t-butyl in the 5-position, R₂ is hydrogen or methyl in the 7-position and B is phenyl, ##STR132## in which R₃ is hydrogen or methoxy, ##STR133## in which R₂ is hydrogen or methyl.
 5. Mixtures of optical brighteners as claimed in claims 1 to 4, consisting of 20 to 80% by weight of a compound of the formula 1 and 80 to 20% by weight of one or more compounds of the formulae 2 to
 6. 